In a system in which a large number of information processing apparatuses connected via a network are present, there is a technique for performing backup of files of the information processing apparatuses via a network.
For example, there is a technique described below. A backup system includes a hard disk, a backup server, a monitoring unit, an extracting unit, an upload unit, a difference generating unit, a user database, and a download unit. The hard disk is connected to a terminal apparatus and accumulates data. The backup server is connected to the terminal apparatus via an IP network. The monitoring unit monitors, on the terminal apparatus side, a data occupancy ratio in the hard disk. The extracting unit extracts data according to a data attribute when the data occupancy ratio is equal to or higher than a predetermined data occupancy ratio. The upload unit transmits the extracted data to the backup server. The difference generating unit is provided on the backup server side and generates difference data between existing data already accumulated and the uploaded data. The user database accumulates the generated difference data. The download unit generates, according to a request from the terminal apparatus side, data for download from the existing data and the difference data and transmits the data for download to the terminal apparatus.
Patent Document 1: WO2005/093579.